It consists of an expansion of over 50% of the lumen of the abdominal aorta and iliac arteries. All of the arteries may be involved, but more often the abdominal aortic district is the most affected, particularly abdominal (85%). The atherosclerosis is the most frequent cause, although there may be other causes such as trauma and infections. The natural evolution of the aneurysm is gradually increasing its diameter, with high risk of rupture, which is a dramatic event that leads to the death of the patient in high percentage of cases, even if operated in urgency. In most aneurysms we can find  thrombi that can detach and be dragged into more distal arterial blood vessels that  become blocked and causing ischemia (embolism), or close the aorta itself. The aneurysm can cause fistulas to the  neighbors; however, all conditions with high mortality.
Usually the diagnosis is through random medical view (abdominal mass) and in particular the vascular surgeon has a capacity not indifferent to detect abnormal pulse with the simple abdominal palpation (only with difficulty in being particularly obese) or as a result of investigations carried out for diagnostic other reasons (ultrasound examinations, CT, MRI).
The surgical indication is absolute trough  traditional surgery (aneurismectomy and replacement with implants) or endovascular percutaneous way  (endoprostheses), in relation to the anatomical aneurismal sac, the general state of health, age, cardiac and pulmonary parameters of each individual.